The energy lifecycle
Combine water and carbon dioxide. If you use some energy take a part of oxygen out - you will be left with the glucose - a simple sugar. Plants use the energy of the sun to run this process all over the planet every day.
Our bodies revert that reaction by adding oxygen back to the glucose (that's the reason you have to breathe :) ) to release the stored energy (water and exhaled carbon dioxide are the waste products). The actual process of converting that energy into muscular(mechanical) one is a bit more complicated, involving the conversion of glucose into the more suitable fuel by the mitochondria.
1 gram of glucose contains 4 calories of energy. You burn that much energy by running for the 40 meters.
Fat is the conserved fuel our body is able to store in a practically infinite amount.
Why and how do we accumulate the fat? Our bodies burn energy at some rate. This rate is higher during the exercise and lowers during the rest. Consumed carbohydrates are broken down into the glucose and used as the primary energy source by the organs (except for the heart, which mainly uses fatty acids for fuel). An insignificant amount of sugar is stored in the muscles in the form of glycogen for quick access, Some glycogen is stored in the liver and released on demand, but not much (enough to sustain a few hour exercise).
If the glycogen stores in your body are already full, and the sugar enters your bloodstream at a higher rate than your body is able to burn it - any excess will be stored as fat for the later consumption.
Some sugars you eat are simple (like glucose, fructose) and easy to digest. Simple sugars combined into complex chains (starches for example) are harder to digest, as they need to be broken down first. Some sugar chains, cellulose, for example, cannot be broken down by the human body at all, therefore pass through it and do not contribute to the overall calory intake.
The simpler sugar is - the quicker it will reach your bloodstream - the greater chance it will be converted into fat.
On the other hand - a can of Coke (33 grams of table sugar) consumed after a 10km run would be used to replenish the glycogen stores and won't end up as a fat.
For both simple and complex carbohydrates 1 gram contains 4 calories of energy, Dietary fiber (cellulose for example) is a carbohydrate as well, but, as mentioned before, it is not absorbed by the humans, as our bodies lack the enzymes which are needed to break it down.
While protein also provides 4 calories per 1 gram - it's primary function is to provide building blocks for the body. Protein will be converted into glucose when glycogen stores in the muscles and the liver are exhausted. While there is a pathway for the excess protein to turn into fat - it is very unlikely to happen. This doesn't mean one can safely replace carbohydrates with protein in the diet - consuming too much of it may overload liver and kidneys,
Another source of energy is the fat we eat. It contains approximately 9 calories per 1 gram. Consumed fat is broken into fatty acids first. Some of the consumed fat is used as the fuel, the rest is used for the different purposes (like an insulator for the nerves and organs or hormone production for example). Fat will slow down the digestion of the carbohydrates and/or proteins when consumed together.
Body weight, BMI, and fat percentage
Body Mass Index is simple but useless. It doesn't differentiate between muscle mass and fat mass.
The person above is the Arnold Schwarzenegger. According to the BMI (height 188cm, weight 106kg) he was obese in 1974, the year this photo was taken :)
There are few variables we can change to affect body mass - muscle mass, fat tissue, and water. Changing the amount of water in your body is neither effective nor healthy way to affect the body weight, therefore we are left with only two variables.
Fitness is rarely about losing weight. Usually, it's about changing the body composition. Being big boned doesn't make you look fat. Being muscular doesn't make you look fat. Fat makes you look fat.
Making the change
Basal Metabolic Rate tells us the amount of energy we burn during the rest per day. Your liver, brain, muscle, kidneys, heart and other organs constantly require energy supply just to keep you alive. Even if you stay completely idle throughout the day - you will still burn 1000-2500 calories (actual amount depends on the lean body mass of the individual).
BMR is the bulk of the daily energy expenditure even for many athletes.
Your approximate BMR is calories per day.
You can reduce your body fat percentage in a number of ways. The most obvious one - simply reduce your daily calory intake to the amount which is less than your BMR combined with any additional calories spent (like during exercise). In other words - eat less - weigh less.
While the diet is the primary way of changing the body composition - it can lead to the undesired result when used as the only way.
Reducing the calory intake below the amount spent will eventually switch the body into the starvation mode. This will trigger the release and use of the stored fat for fuel. It will also trigger the gluconeogenesis - the process of converting proteins and fats into glucose. Not all organs can use fats as the fuel - our brain requires at least 10g of glucose per day, the remaining energy requirements of the brain are satisfied by the alternative fuel produced by the liver from the fat. The body may break down the muscle tissues, which are made of protein in case there is not enough of it in the bloodstream to convert into glucose. In other words - you may end up losing both fat and a significant amount of the muscle mass as a result - depends on how extreme the diet is.
Increased protein intake can mitigate the muscle mass loss problem to some extent, but it's not a silver bullet and you can't consume a lot of it due to the reasons explained earlier.
It's hard to spot muscle mass loss if you are overweight - a layer of fat may mask it.
The consequence of losing the muscle mass is the daily energy expenditure (BMR) decrease (as it directly depends on the lean body mass). Lower BMR means the energy demand is now lower than it was before, therefore calory intake should be reduced or the amount of exercise has to be increased. Ever heard of the yo-yo weight cycling effect? Decreased BMR is one of the reasons people start gaining, even more, weight when they complete the diet and return to their usual eating habits.
When diet is combined with an aerobic exercise like running, cycling, swimming - energy consumption is accelerated. A lot of calories are burned during the aerobic exercise - approximately 100 calories per 1km of running or 5km of cycling for example (it depends on your weight and age and exercise conditions).
Human body prefers fat as the fuel source during the low-intensity exercise, such as aerobic one, therefore it's a good choice to lose fat. The duration is important - 40 minutes or more is the way to go.
Fat is very energy dense - with 9 calories per 1 gram, it's 9000 calories per 1 kilogram of fat. That's 90 kilometers of running alone! Think of it this next time you eat your 200 calory snack :)
The best way to affect your body composition is to grow muscle mass while keeping slight calory deficit and doing occasional aerobic exercise. Increased muscle mass will result in higher BMR. As the baseline energy demand will grow - you'll have to eat more, simply to keep slight calory deficit constant. That's where the "to lose weight you have to eat more, not less" expression stems from. It takes a longer time to achieve the goal, but the result is much more sustainable.
So, how do you become more muscular? The answer is simple - you lift. You lift heavy weights. How heavy? Think weight, which you can lift 8-12 times max. The weight will be different for different types of exercise. Lifting heavy weights will:
- Increase the production of the testosterone in the body.
- Do some damage to the muscle fibers. Combined with the increased muscle protein synthesis due to the raised testosterone level this will promote the muscle growth.
Lifting light weights will not result in testosterone production increase. Muscle will not grow if testosterone level does not increase. No pain - no gain. You have to overload the body to trigger the response.
Testosterone is only produced when you rest(sleep), therefore you will experience the boost on the day following the strength exercise. The heavier the weight you lift and the more joints are involved in the exercise - the stronger effect it will have on the testosterone production.
If you are a beginner - don't waste your time on weight machines. Most of those are isolation (single-joint) oriented and won't affect hormone production much. Dedicate first years of your training to the compound (multi-joint) exercises. The following are the classics:
Each of the mentioned above will result in a huge boost in testosterone production, but beware all three are the high-risk exercises and will result in injury if performed improperly. A proper warm-up before lifting heavy weights is essential. Please learn about proper form and common mistakes (see deadlift, squat and bench press mistakes for example) before starting. Start with lighter weights, only go heavier if you are completely confident and comfortable with the exercise.
Proper rest is required to allow full muscle recovery between workouts. Too frequent exercise may lead to overtraining.
Due to the physiological differences, it's easier for the males to gain muscle mass compared to the females. It's nearly impossible for the most females to become as muscular as the Arnie on the photo above, simply because testosterone production volume is lower in females than males.
The human body needs amino acids to repair and grow the muscle tissue. There are 20 common amino acids, nine of which are essential (our body cannot synthesize those from other common amino acids). We get amino acids from the protein we consume. Different proteins contain different sets and amounts of the mentioned common amino acids. Complete proteins contain all nine essential amino acids. Meat, dairy, eggs, soy, and fish are sources of the complete protein.
You'll have to adjust your protein intake after starting the weight training, but don't go crazy about it. 1.5 grams of protein per one kilogram of the desired body mass is enough in most cases (for an 80kg person - that's 120 grams of protein per day). For the reference - 100 grams of chicken breast contain 31 gram of complete protein, one egg (one of the best protein sources) has 6 grams of protein.
It's easier than you think
Eat clean. High-calory fast carbohydrates are too expensive - think in terms of kilometers of running needed to burn those.
Run a few km twice a week - that's extra several hundred of calories burned.
Do 40 minutes of weight lifting two-three times a week. Spend those 40 minutes working out, not looking at your phone.
And sleep well.